Fiber reinforced laminated plastic film and method of making same

ABSTRACT

An improved fiber reinforced laminate, in which the nonwoven reinforcement is oriented in four different planes, each of the four containing fibers parallel with each other. Describing the construction in another way, it consists essentially of two diamond patterns superimposed on each other, one of which has its longer diagonals parallel with the longitudinal direction of the laminate (the machine direction), and the other has its shorter diagonal parallel with this direction. The invention also contemplates a method for mass producing this laminated article, by means of modulating the speed of the fiber angularizing means of the laminate producing machine.

Umted States Patent 1151 3,644,165 Chen 1 1 Feb. 22, 1972 [54] FIBERREINFORCED LAMINATED 2,313,581 3/1943 Reed ..161/143 PLASTIC FILM ANDMETHOD ()1? 2,851,329 9/1958 Lappala.... ....161/139 X 2,999,0 1 9 1961Lappala... ....161/144 X MAKING SAME 3,314,841 4/1967 Romanin......161/143 X [72] Inventor: Wei-Gwo Chen, Houston, Tex. 3,445,3195/1969 Dawbam ..161/59 X [73] Assisnee: Grmolyn p y Incorporated3,511,739 5/1970 l-lebberlmg ..161/57 22 Filed; 0 15 19 9 PrimaryExaminen-RobertF. Burnett Assistant Examiner-Raymond O. Linker, Jr. PP8661599 Attorney-Johan Bjorksten 521 user. ..161/58, 156/177, 156/179,[57] ABSTRACT 156/439, 161/ 143, 161/144 An improved fiber reinforcedlaminate, in which the non- [51] Int. Cl. ..B32b 5/08 wovenreinforcement is oriented in four different planes, each [58] Held atSearch ..156/177, 179; 161/55, 57, 58, f th f ur containing fib rsparallel with each other. D scrib- 161/59, 78, 109, 113, 142, 143 144ing the construction in another way, it consists essentially of twodiamond patterns superimposed on each other, one of [56] ReferencesCited which has its longer diagonals parallel with the longitudinaldirection of the laminate (the machine direction), and the UNITED STATESPATENTS other has its shorter diagonal parallel with this direction. Theinvention also contemplates a method for mass producing this Jenkins Xlaminated article, means of modulating the speed of the 60949 7/1923fiber angularizing means of the laminate producing machine. 1,571,5792/1926 10 Claims, 6 Drawing Figures FIBER REINFORCED LAMINATED PLASTICFILM AND METHOD OF MAKING SAME This invention relates to flexiblefoldable laminates which are reinforced by means of diamond patternednonwoven fiber structures, and in which the reinforcing fibers betweenany two film surfaces lie in at least four different planes, and areparallel within these planes. In referring to four planes, I haveparticular reference to those points where all of the fibers cross overeach other, due to the sagging between crossover points the fibers maybend into the same under influence of pressure, but if through tensionor otherwise the fibers are rigidized, they will be structurally in fourdifferent planes.

Heretofore, reinforced plastics are well known, and diamond structurehas been disclosed, for example, in U.S. Pat. Nos. 2,851,389 and2,999,041. However, in these structures of prior art, no more than twogeometrically regular polygonal reinforcements have been present betweenany two films, because of the mechanical difficulties heretoforeencountered in effecting such arrangements.

Inasmuch as the strength of such films is almost entirely due to thefibers rather than the films, and the orientation of fibers will controlthis strength to a very high degree, it is apparent that the optimalarrangement will be constituted of a grouping of parallel fibers, inwhich the parallel groups form angles with each other in the order of45, rather than 90, so that a substantial number of fibers will coact onpulls from directions intermediate between the longitudinal and thetransverse directions of the laminates as well as in these directions.

An object of this invention is a flexible, foldable plastic filmlaminate of exceptional strength.

Another object is a flexible, foldable plastic film laminate in whichthe fibers of the reinforcement are placed in at least four differentplanes between the films, are substantially parallel in each of saidplanes and are placed substantially in four different directions betweeneach pair of films, the angle between any two adjacent of the planes orlayers being in the general order of 35 to 55.

Another object is the method for producing such laminates.

Further objects will become apparent as the following detaileddescription proceeds.

Reference is being made to the drawings of which FIG. I and 2 are topviews,

FIG. 3 is a typical cross section of the laminate, greatly enlarged, and

FIG. 4 is a top view of the part of the machine for making the laminate,and

FIG. Sis a side view of the same device.

FIG. 6 is a schematic view showing the two component patterns of thefilm laminate of this invention separated from each other for the sakeof clarity.

In accordance with my invention, I prepare, preferably by machine, butby hand layup if necessary, a fiber pattern such as shown most clearlyin FIG. 6, where one pattern is a crisscross of the fibers 1 and 2 andfibers parallel with I and 2, at a spacing between fibers usuallybetween one-sixteenth and 2 inches from each other and preferablyone-fourth to threeforths inches from each other, in which the saidfibers in each plane do not intersect but all the fibers 1 are parallelin one plane and all the fibers in the direction of fiber 2 are parallelin the other plane. This is placed automatically or by hand on top ofanother grate which is similar, except that the diamond pattern formedby fibers 1 and 2 has the long diagonal parallel with the machinedirection of the product while the diamond pattern formed by fibers 3and 4 has the short diagonal parallel with the machine direction, all ofthe these diamonds having their smaller angle between 10 and 40 andpreferably between 20 and 33. When these two diamond structures aresuperimposed upon each other, there results a structure such asillustrated in FIGS. 1 and 2, where fibers are positioned not about 90divergent from each other, so as to be in a much better position to meetcertain pulls or stresses from different directions. Such fiberarrangement has long been viewed as an ideal; however it has notpreviously been possible to make them in a practical manner.

The construction of this invention is particularly attractive, becauseit can be manufactured at speeds of several hundred feet per minute,utilizing. existing equipment with only a very small addition, namelythat of a second fiber angularizer. This arrangement is illustrated inFIG. 5. Plastic films 5 and 6, coated on one side with an adhesive andprovided with antiadhesion coating on the other side so that the otherside can be rolled up against the adhesive layer are passed from rollers13 and 14 into the bite of two laminating rollers 11 and 12. Betweenthem, also fed into the same bite of the same laminating rollers, arefiber supplies 8 and 7, which are passed through angularizers 9 and 10which cause the said fibers to become crossed at angles, depending uponthe ratio of fiber supply, speed and crossover speed in the angularizer.These ratios are set so as to produce fibers crossing each other to forma diamond pattern, in which the small angle is between 10 and 40 andpreferably between 20 and 35. The antiadhesion coating can be dispensedwith if the film is laminated immediately following the application ofthe adhesive. The adhesive can be dispensed with if the fibers are heldin a heat sealing or extrusion union of the films being laminated. Inthe term lamination, I include the process of forming a union of twofilms by extruding or casting one of the films onto the other. Thelayers and/or the films may be multiple, but at least two sets ofcrossed fibers forming two diamond patterns are essential.

These diamond patterns then become superimposed over each other andlaminated between the said adhesives. From the laminating roller, theresult laminate 15 passes on to the receiving roll 16.

The angularizer can be of any construction known in the art. It is notpart of this invention. I may employ for example the angularizerdisclosed in US. Pat. No. 3,156,027 or it may be based on areciprocating comb which lays down the fibers in a crisscross as itpasses reciprocatingly across a tenter frame type of arrangement, or itmay be a revolving creel with fiber guides carried through eyelets on achain revolving around a carrier medium such as a film of polyvinylalcohol which is subsequently dissolved in water, leaving the fibers inthe diamond pattern desired.

Any of these arrangements are satisfactory and usable so far as thisinvention is concerned.

As for the films, I can employ any flexible, foldable plastic film ofadequate strength, and the same applies to the fibers. For example,these may be of polyolefins, including polyethylene, polypropylene, andtheir copolymers, of cellulosic materials, natural or synthetic,polyvinyl halide including the chloride and the fluoride, polydiethyleneglycol terephthalates and other polyesters of fibrous nature, andpolyvinylidine halides, polycarbonates, polyoxyphenols, nylon-typepolyamides, including also such fibers and films of properties similarto those mentioned, which have not yet been invented, but may beappearing on the market at some future time during the validity of anypatent or continuation thereof.

The adhesive can be any type of industrial adhesive that holds togetherthe fibers and the films discussed, including for example, natural andsynthetic rubber glues, hot melt composition of cellulose esters andethers, polyvinyl acetal, polyamides and polyethylenes of molecularweight sufficiently low to ensure tackiness, copolymer of ethyl acrylateand polyacetate, and the like. Since formulations of adhesives are wellknown in the art and disclosed in the patents cited above, it isbelieved superfluous here to discuss this noncritical factor in detail.

It is thus seen that the present invention is broad in scope and is notto be restricted by the specific examples here given but construed asbroadly as is consistent with the prior art and the claims.

Having thus disclosed my invention, I claim:

1. A multidirectional fiber reinforced laminate which is flexible andfoldable and which contains at least four separate layers of reinforcingfibers disposed between a pair of plastic films, said laminate having amachine'direction and a crossdirection, the fibers in each layer beingsubstantially parallel with each other, characterized by:

the fibers in the first layer being disposed at an angle to those in thesecond layer so that the fibers of the first and second layers formdiamond patterns,

each of the diamonds of said pattern having four edges, two

opposite edges being defined by two fibers of said first layer and theother two opposite edges being defined by two fibers of said secondlayer, each of said diamonds having two acute angled corners and twoobtuse angled corners defined by said edges and having a long axisextending between said acute angled corners and a short axis extendingbetween said obtuse angled corners,

the fibers in the third layer being disposed at an angle to those in thefourth layer so that the fibers of the third and fourth layers formdiamond patterns, each of the diamonds of said pattern having fouredges, two opposite edges being defined by two fibers of said thirdlayer and the other two opposite edges being defined by two fibers ofsaid third layer and the other two opposite edges being defined by twofibers of said fourth layer,

each of said diamonds having two acute angled corners and two obtuseangled corners defined by said edges and having a long axis extendingbetween said acute angled corners and a short axis extending betweensaid obtuse angled corners,

the long axes of the diamonds in the diamond pattern of the first andsecond layers extending substantially in the machine direction, and

the long axes of the diamonds in the diamond pattern of the third andfourth layers extending substantially in the cross-direction,

so that none of the fibers extend substantially in either the machinedirection or the cross-direction.

2. The laminate of claim 1 wherein the acute angles of the diamonds inone of said diamond patterns are from to 40.

3. The laminate of claim 1 wherein the acute angles of the diamonds inboth of said diamond patterns are from 10 to 40.

4. The laminate of claim 1 wherein the acute angles of the diamonds inone of said diamond patterns are between 20 and 33.

5. The laminate of claim 1 wherein the acute angles of the diamonds inboth of said diamond patterns are between 20 and 33.

6. The method of manufacturing a multidirectional fiber reinforcedlaminate which is flexible and foldable and which contains at least fourseparate layers of reinforcing fibers disposed between a pair of plasticfilms, said laminate having a machine direction and a cross-direction,the fibers in each layer being substantially parallel with each other,which comprises the steps of:

supplying to a laminator two plastic fiber webs, and, between said webs,a first layer of substantially parallel fibers, and, a second layer ofsubstantially parallel fibers, and, a third layer of substantiallyparallel fibers, and, a fourth layer of substantially parallel fibers,the fibers in the first layer being disposed at an angle to those in thesecond layer so that the fibers of the first and second layers formdiamond patterns, each of the diamonds of said pattern having fouredges, two opposite edges being defined by two fibers of said firstlayer and the other two opposite edges being defined by two fibers ofsaid second layer, each of said diamonds having two acute angled cornersand two obtuse angled comers defined by said edges and having a longaxis extending between said acute angled corners and a short axisextending between said obtuse angled comers, the fibers in the thirdlayer being disposed at an angle to those in the fourth layer so thatthe fibers of the third and fourth layers form diamond patterns, each ofthe diamonds of said pattern having four edges, two

opposite edges being defined by two fibers of said third layer and theother two opposite edges being defined by two fibers of said fourthlayer,

each of said diamonds having two acute angled corners and two obtuseangled corners defined by said edges and having a long axis extendingbetween said acute angled corners and a short axis extending betweensaid obtuse corners,

the long axes of the diamonds in the diamond pattern of the third andfourth layers extending substantially in the corss-direction,

so that none of the fibers extend substantially in either the machinedirection or the cross-direction,

and laminating said webs and layers together.

7. The method of claim 6 wherein the acute angles of the diamonds in oneof said diamond patterns are from 10 to 40.

8. The method of claim 6 wherein the acute angles of the diamonds inboth of said diamond patterns are from 10 to 40.

9. The method of claim 6 wherein the acute angles of the diamonds in oneof said diamond patterns are between 20 and 33.

10. The method of claim 6 wherein the acute angles of the diamonds inboth of said diamond patterns are between 20 and 33.

2. The laminate of claim 1 wherein the acute angles of the diamonds inone of said diamond patterns are from 10* to 40*.
 3. The laminate ofclaim 1 wherein the acute angles of the diamonDs in both of said diamondpatterns are from 10* to 40*.
 4. The laminate of claim 1 wherein theacute angles of the diamonds in one of said diamond patterns are between20* and 33*.
 5. The laminate of claim 1 wherein the acute angles of thediamonds in both of said diamond patterns are between 20* and 33*. 6.The method of manufacturing a multidirectional fiber reinforced laminatewhich is flexible and foldable and which contains at least four separatelayers of reinforcing fibers disposed between a pair of plastic films,said laminate having a machine direction and a cross-direction, thefibers in each layer being substantially parallel with each other, whichcomprises the steps of: supplying to a laminator two plastic fiber webs,and, between said webs, a first layer of substantially parallel fibers,and, a second layer of substantially parallel fibers, and, a third layerof substantially parallel fibers, and, a fourth layer of substantiallyparallel fibers, the fibers in the first layer being disposed at anangle to those in the second layer so that the fibers of the first andsecond layers form diamond patterns, each of the diamonds of saidpattern having four edges, two opposite edges being defined by twofibers of said first layer and the other two opposite edges beingdefined by two fibers of said second layer, each of said diamonds havingtwo acute angled corners and two obtuse angled corners defined by saidedges and having a long axis extending between said acute angled cornersand a short axis extending between said obtuse angled corners, thefibers in the third layer being disposed at an angle to those in thefourth layer so that the fibers of the third and fourth layers formdiamond patterns, each of the diamonds of said pattern having fouredges, two opposite edges being defined by two fibers of said thirdlayer and the other two opposite edges being defined by two fibers ofsaid fourth layer, each of said diamonds having two acute angled cornersand two obtuse angled corners defined by said edges and having a longaxis extending between said acute angled corners and a short axisextending between said obtuse corners, the long axes of the diamonds inthe diamond pattern of the third and fourth layers extendingsubstantially in the corss-direction, so that none of the fibers extendsubstantially in either the machine direction or the cross-direction,and laminating said webs and layers together.
 7. The method of claim 6wherein the acute angles of the diamonds in one of said diamond patternsare from 10* to 40*.
 8. The method of claim 6 wherein the acute anglesof the diamonds in both of said diamond patterns are from 10* to 40*. 9.The method of claim 6 wherein the acute angles of the diamonds in one ofsaid diamond patterns are between 20* and 33*.
 10. The method of claim 6wherein the acute angles of the diamonds in both of said diamondpatterns are between 20* and 33*.